1. Field of the Invention
The field of the invention is that of the semiconductor optical devices used in particular for fibre-optic telecommunications.
A fibre-optic telecommunications device essentially comprises optoelectronic devices for optical signal generation, transduction, shaping and amplification and optical fibres for connection.
After travelling through a standard optical fibre, knowledge of the polarization the state of the initial optical signal is lost. The optoelectronic devices used for receiving this signal consequently needed to have characteristics and properties which are independent of the polarization. It is very difficult to obtain such devices with integrated components, which are generally sensitive to the polarization state. Optical amplifiers are a particular example. It is possible to use discrete components which are less sensitive to the polarization state, albeit of course to the detriment of the cost and the bulk of the system.
2. Description of the Prior Art
To overcome this drawback it is possible to use systems with polarization diversity, which separately process two orthogonal polarizations obtained by projecting the polarization of the signal onto two orthogonal axes. A polarization splitter is then used, which is currently available either in free optics or in integrate optics. In the latter case the component has dimensions of more than one millimetre, these dimensions being dictated by the components used to produce the half-wave plate needed for splitting the polarizations.